Use of electrical current, especially in the area of anodynia, more specifically in the area of pain relief, has been known for several decades. The first reports of the use of electrical current for pain management appeared in the 1930's. Initially, DC was used to induce lesions of nerves through the temperature increase caused by the electrical current (thermocoagulation). Later, this has been replaced by AC with a frequency of 400 to 500,000 Hz, which has been shown to deliver more precise lesions. In the past few decades this radiofrequency (RF) thermocoagulation has been established as an accepted treatment option for trigeminal neuralgia, for unilateral cancer pain and for zygoapophyseal joint pain. Further, RF has been used in other fields:                in cardiology for thermocoagulation of conductive tissue in the heart that conduct aberrant stimulus patterns;        in oncology for destroying tumor tissue;        in orthopedics for treatments of cartilage defects in osteoarthritis.        
The therapeutic effect was mainly concerned with the destruction of tissue by the heat that was generated by the current. The development of a novel method for administrating high frequency current, pulsed radiofrequency (PRF) allowed using it to treat other pathologies and nerve structures. With PRF, current is delivered in pulses of short duration (1-100 msec) separated by a silent period of about 0.1 to 1 sec. Output current may be set not to exceed 42° C. to prevent cell destruction. Heat generated by the application of the current is dissipated between pulses. Nowadays PRF is recognised as treatment for e.g. various forms of spinal and facial pain and peripheral neuralgias.
The mechanism through which PRF causes long-lasting pain relief when applied in the vicinity of a nerve is not known.
In the meantime, it has been published by the present inventors (WO 2008/094042) that PRF has beneficial effects on seeds and the germination of seeds. Although also the mechanism that causes these effects is not yet elucidated, it appears that PRF is capable of influencing biological tissue to perform better.
Except for pain relief no further clinical therapies involving PRF have been established.